In recent years, a MIMO system using a plurality of transmit/receive antennas has been proposed as a method for increasing a data transmission capacity in a wireless communication system. The SDM (Space Division Multiplexing) scheme and the STC (Space Time Codes) scheme may be employed in the MIMO transmission system. Further, a proposed example of implementing the MIMO system includes, for example, a dual-polarized MIMO method that simultaneously employs both horizontal and vertical polarizations.
The MIMO transmission using a plurality of transmit/receive antennas may be implemented through an actual transmission path expected to be use for broadcasting services. In such the case, sometimes, a reception level of signals received by only one of the receive antennas has significantly fallen down, due to a difference in reflection characteristics and/or another factor. In the SDM transmission scheme, since the plurality of antennas respectively transmit separate streams, the decrease of the reception level in one of the receive antennas causes the deterioration in the individual BER (Bit Error Rate) characteristic, resulting in a drastic deterioration of an overall BER characteristic of the system as a whole.
In order to improve the performance of the error correction code in the ISDB-T (Integrated Services Digital Broadcasting—Terrestrial) system currently introduced in Japan as the digital terrestrial broadcasting format, a bit interleaving, a time interleaving and a frequency interleaving are employed for rearranging the order of transmission data (for instance, set forth in NPL 1). Further, the interleaving scheme of the IEEE802.11 may be expanded to the MIMO system. In this connection, conventionally known is a technical method for distributing a single stream among a plurality of transmitters in a bit unit so as to implement the bit interleaving in units of each transmitter (for instance, set forth in PTL 1).